60. Oesophagus - a) Ontogenesis (including embryogenesis) = How the oesophagus forms and grows before birth Flashcards
(28 cards)
What does ontogenesis mean?
It means how a body part develops and grows from a small group of cells into a full structure.
What is embryogenesis?
The part of ontogenesis that happens during the embryo stage (early development before the baby is fully formed).
Which part of the early gut tube forms the oesophagus?
The foregut (the front part of the primitive gut tube).
When does the oesophagus start to form?
Around week 4 of pregnancy.
Why does the oesophagus get longer?
Because the heart and lungs move down into the chest, pulling the oesophagus longer.
Which layer gives rise to the oesophagus inner lining?
The endoderm (inner layer).
Which layer gives rise to the oesophagus muscle?
The mesoderm (middle layer).
How do the oesophagus and trachea stay separate?
A wall called the tracheoesophageal septum forms between them.
By which week is the oesophagus fully shaped as a tube?
By about week 8 (end of the embryonic period).
What does the foregut also develop into besides the oesophagus?
It also develops into the stomach, part of the small intestine, and the trachea (windpipe).
What happens if the tracheoesophageal septum does not form properly?
The baby may have a condition like tracheoesophageal fistula (an abnormal connection between oesophagus and trachea).
Which germ layer is NOT directly involved in oesophagus formation?
The ectoderm (outer layer).
What is the main role of the mesoderm in the oesophagus?
To form the muscle layers that help move food down (peristalsis).
Why is lengthening of the oesophagus important?
To match the growing distance between the throat and stomach as the chest expands.
During which pregnancy weeks does the embryonic period take place?
From fertilization to week 8.
What is the primitive gut tube?
An early tube in the embryo that later divides into the foregut, midgut, and hindgut to form the digestive system.
What happens to the oesophagus after week 8?
It continues to grow in length and muscle thickness before birth.
Why is the oesophagus lining made from endoderm?
Because the endoderm forms the internal lining of the digestive system.
What type of muscle develops around the oesophagus?
Smooth muscle (for involuntary movements) and some skeletal muscle near the top.
Which part of embryogenesis forms the oesophagus lining?
The endoderm layer (inner germ layer).
Which part of embryogenesis forms the oesophagus muscles?
The mesoderm layer (middle germ layer).
At which embryonic week does the oesophagus begin to form?
Around week 4.
Which embryonic structure does the oesophagus come from?
The foregut.
What important separation happens during oesophagus embryogenesis?
Formation of the tracheoesophageal septum, separating oesophagus and trachea.
